Apartment under construction purchase documents

Hi, I am planning to buy a new apartment (under construction) from the builder by applying a housing loan in Pondicherry. I have few queries: 1. As per builder, I will be getting UDS sale deed (after registration) and Memorandum of Agreement document now, and after the construction they will provide the completion certificate. Are they enough legally? Should I get any other legal documents from the builder ? 2. If only UDS sale deed and Memorandum of Agreement is enough, then what are the keys words I should look for? Please let me know the necessary documents / registration process to buy the under construction property.